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Re: LF: Re: Active antennas on 136kHz, additional wire needed?

To: "Alan Melia" <[email protected]>, [email protected]
Subject: Re: LF: Re: Active antennas on 136kHz, additional wire needed?
From: [email protected]
Date: Tue, 29 Sep 2015 15:05:02 +0200
In-reply-to: <[email protected]>
References: <[email protected]>, <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
Hello Chris,

The "PCB-antenna" is equivalent to a 1 feet rod and though counter 
intuitive, adding one won't help.

As with all active whip designs, at VLF / LF / MW and lower HF the 
whip is NOT the antenna.

How the pa0rdt-Mini-Whip© works, can be found here:

http://wwwhome.cs.utwente.nl/~ptdeboer/ham/tn/tn07.html

Though some knowledgeable people don't agree, I have put the theory
to the test and build a battery powered mini-whip with the battery 
included in the antenna housing. The rf was transported by a 
optical fibre link. The antenna was mounted on a non conducting 
fibre glass pole.

Nothing was received at all with this set up, until I put a coax 
cable up the mast ending 5 cm below the antenna. There was no 
connection between this cable and the circuit board, whatsoever.
The shield of the coax cable was connected to a ground stake at the 
bottom of the mast and it provided the necessary ground reference 
for the ohterwise isolated antenna.

I hope this helps.

73,
Roelof Bakker, pa0rdt

N.B. Rather than building one for one's own use, which is no problem 
at all, I am sorry to find that some people are making money from a 
copywrighted design. (Readily build antennas are available from the 
designer for those unable or unwilling to build one.)


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